MathGroup Archive 2003

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: input without output

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39116] Re: input without output
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 30 Jan 2003 01:05:54 -0500 (EST)
  • Organization: Universitaet Leipzig
  • References: <b184f1$kqe$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

you should fix you StandardForm[] input it is

InverseFourierTransform[
  Sum[DiracDelta[1000(-1 + 10^(fHat/c))/b - f], {fHat, 0, N}], f, t]

and it is no wonder that Mathematica can't find a result because
a) N[] is used to convert a exact number into a floating point value
b) N has no value, espacial in you expression it can be 0 
c) Mathematica must Solve[1000(-1 + 10^(fHat/c))/b - f== 0,fhat]
   and find out if the solution lies between 0 and N and this 
   can't be done without a knowlege about N

Regards
  Jens

Matt Flax wrote:
> 
> Thefollowing input generates no answer (mathematica 4.2) :
> 
> (*I re-write it so it is easier to read*)
> 
> InverseFourierTransform[
>         Sum[
>                 DiracDelta[1000(-1 + 10^(fHat/c))/b - f],
>         (fHat = 0),N],
> f,t]
> 
> (*Which is the same as*)
> Notebook[{
> Cell[BoxData[
>     \(
>       InverseFourierTransform[\[Sum]\+\(fHat = 0\)\%N DiracDelta[
>             1000 \((\(-1\) + 10^\(fHat\/c\))\)\/b - f], f,
>         t]\)], "Input"]
> },
> FrontEndVersion->"4.2 for X",
> ScreenRectangle->{{0, 1280}, {0, 1024}},
> WindowSize->{959, 890},
> WindowMargins->{{0, Automatic}, {Automatic, 0}}
> ]
> 
> Any ideas ?
> thanks
> Matt
> --
> http://mffm.darktech.org
> 
> WSOLA TimeScale Audio Mod  : http://mffmtimescale.sourceforge.net/
> FFTw C++                   : http://mffmfftwrapper.sourceforge.net/
> Vector Bass                : http://mffmvectorbass.sourceforge.net/
> Multimedia Time Code       : http://mffmtimecode.sourceforge.net/


  • Prev by Date: Re: plotting several 3D-functions
  • Next by Date: Re: Re: Gaussian intersection
  • Previous by thread: input without output
  • Next by thread: Re: What is -- Fractional integro-differentiation